1. Field of the Invention
The present invention relates generally to pipe laying equipment, and more particularly to a tool for use with an excavator for supporting a length of pipe while lowering the pipe into a trench and connecting it to a second length of pipe.
2. Brief Description of the Prior Art
The process of laying sections of pipe for an underground pipe line involves first digging a trench to the required depth. A heavy mobile piece of equipment known as an excavator is then typically used to lower a section of pipe into the trench. The pipe is secured to an end of an arm or boom of the excavator with chains and C-hooks.
A disadvantage of this method is that it is necessary to place a worker in the trench to guide the newly lowered section of pipe into contact with a previously installed section. The worker must also disengage the C-hooks and chains from the pipe. The task of manipulating the pipe in the trench is not without some hazard, due in part to the weight of the pipe and excavator arm. In deep trenches, the additional hazard of possible collapse of the trench walls must be carefully guarded against for the safety of the trench worker. In cases where there is danger of wall collapse, shoring is often put in place to support the soil. The shoring must then be removed and reinstalled for the process of laying the next section or sections of pipe, etc.
U.S. Pat. No. 5,232,502 by Recker describes an apparatus designed to lay pipe with an excavator without the need for a worker in the trench. A horizontally positioned arm 78 is suspended from the working end of an excavator boom assembly, attached with a rotary coupler 76 (FIG. 2 and col. 3, lines 31-32). In order to avoid the need for a worker in the trench to apply pipe sealant, a sealant is forced through the rotary coupler and sprayed from the end of the horizontal arm. The apparatus as described has some disadvantages and is not in common use. The rotary coupler with conduit is not a standard quick coupler, and requires special modification of the excavator. Connecting the horizontal arm 78 and conduit requires a second worker, or alternatively the excavator operator has to leave the cab to manually perform the operation. Positioning the arm 78 and support beam 80 in the process of connecting the tool to the excavator arm assembly is also a problem due to the weight of the tool, and the fact that without other support, the tool could only lay on the ground, 90 degrees disoriented, requiring an operator, probably with additional equipment to lift it into position for connecting to the excavator coupling device 70. In addition, the rotary connection 76 is not durable enough to withstand repeated use, or rigid enough to allow undesired rotation of a pipe placed on the arm 78. For example, a typical eight foot section of 54 inch diameter concrete pipe weighs about 1370 pounds per foot, or a total of 10,960 pounds. A much more rigid and strong connection is required for practical use.
It is apparent that an improved tool and method of laying pipe is needed that keeps workers out of the pipe trench, and that is robust and can be used with a standard excavator arm quick coupling device.